| 摘要 |
A bipolar transistor has a first semiconductor region of an n-type epitaxial layer surrounded by a first insulating film, a second insulating film of silicon oxide having an opening, a second semiconductor region as a base link region of a p-type formed in the opening and having a high impurity concentration and a thickness substantially the same as that of the second insulating film, a third semiconductor region as an intrinsic base of a p-type having a thickness thinner than that of the second insulating film, a sidewall insulating film covering the third semiconductor region, and a fourth semiconductor of a p-type formed on the third semiconductor region and surrounded by the side-wall insulating film. The reduction in the thickness of the intrinsic base is achieved without reducing the thickness of the base link region and thus it is possible to realize a bipolar transistor in which a cut-off frequency is high and yet the base resistance is low.
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